Village officials begin paring options for upgrading west side of Bridge St. structure, removing sediment

Grafton officials continue to weigh their options for upgrading the village’s Bridge Street dam and dredging the adjoining millpond.

After listening to engineering reports and public input during a meeting Monday, the Village Board pared the list of possible improvements by eliminating a proposal to enlarge the dam weir at a cost of at least $1 million.

The focus of the meeting was the west abutment of the downtown dam, which the village must upgrade by 2019 to meet state flood-control requirements. In a study presented to the board, Bonestroo engineer Dale Buser outlined three main upgrade options:

n Replacing a masonry wall with a concrete wall, raising the riverwalk and reconfiguring the public overlook area. The cost is estimated at $170,000 to $205,000.

n Installing gates to provide flood control and allow dewatering of the reservoir, which would reduce the cost of dredging and allow the dam to be inspected. Depending on the size and type of gates, the cost estimates range from $550,000 to $1.6 million.

n Enlarging the weir for flood control and to create additional recreational activities such as canoeing and kayaking. Estimated costs range from $1 million for a 150-foot weir to more than $2 million for a 1,000-foot weir.

All three options would meet state flood-control requirements, Buser said. However, enlarging the weir “would facilitate recreational activities and provide a potential revenue source for whitewater park events,” he added.

Village President Jim Brunnquell said he appreciated the idea of exploring a variety of options for dam improvements but urged the board to adhere to the spirit of an April 2010 referendum in which residents voted to preserve the dam until at least 2019. That vote didn’t include significantly altering the landmark, he said.

“In my opinion, the referendum would preclude option No. 3 (enlarging the weir). That would change the whole fundamental look of the dam,” Brunnquell said.

At Brunnquell’s suggestion, the consensus of the board was to ask Village Engineer Dave Murphy and his staff to create “a hybrid of the first two options” — replacing the masonry wall and adding a gate to improve flood control.

Trustee Lisa Uribe Harbeck questioned if having a gate in the dam upgrades would increase the risk of spreading invasive aquatic species. In reviewing plans for a proposed fish passage Ozaukee County wants to build in upgrading the east abutment, the Department of Natural Resources announced last month it intends to deny a permit request for that project due to concerns about invasive species.

A final DNR decision on the permit request is expected by the end of July.

“The problem I have is a gate,” Uribe Harbeck said. “That’s not what the DNR is requiring us to install. I want to do what it takes to meet those requirements.”

The board also considered a Bonestroo report on options for dredging, a process that would remove sediment to create a more scenic impoundment, improve water quality and allow more recreational activities on the Milwaukee River.

Engineer Brian Lennie said three areas were identified for possible dredging, which was estimated to cost $13 per cubic yard for mechanical removal and $60 per cubic yard for hydraulic removal. These include a 24,400-cubic-yard area along the west bank north of Veterans Memorial Park, a 1,560-cubic-yard area just north of the Washington Street bridge and a 1,314-cubic-yard area just south of the Washington Street bridge.

Bill Harbeck, Trustee Harbeck’s husband and a member of the Save the Dam Association whose petition drive led to the April 2010 referendum, urged the board to dredge material north of Washington Street near River Island Park.

“I fully support the village’s goal of dredging areas,” Harbeck said. “The area by River Island Park is a disaster. It looks awful.”

Lennie said dredging the River Island Park area was originally considered for the options list, but the DNR said it would not permit dumping sediment in the park. That would probably make hauling the sediment to an alternate location too costly, he said.

Tentative plans call for hauling sediment from other areas to land north of the Grafton High School athletic field, Lennie said.

Brunnquell said the main focus of the board at this time is upgrading the dam’s west abutment. However, the dredging work needs to be done as well, he added.

“The cheapest cost is not necessarily the cheapest cost today,” Brunnquell said. “We don’t want to have to revisit this again in 10 or 15 years.”

The board gave no specific direction to Murphy on dredging, instead asking him to include the work in some form in his recommendations to the Public Works Board on Aug. 8. The Works Board is then scheduled to make a recommendation to the Village Board.

Village Administrator Darrell Hofland said he expects a final decision by Aug. 22, in time for the village to apply for a DNR grant to help fund dam upgrades.

Under the grant program, the village could receive up to $400,000 as part of a matching-fund agreement that requires it to pay 75% of project costs. The grants do not cover dredging work.

The DNR is scheduled to announce the grant recipients Nov. 15, Hofland said.

The village is expected to pay for dam upgrades using revenue from the downtown tax incremental financing district rather than the general tax role — a decision which voters supported in an advisory referendum in April 2010.

The district’s project plan was amended in October 2010 to include cost estimates of $750,000 for dam repairs and $250,000 for dredging work. However, Hofland those expenditure amounts are not binding.

Hofland said the project plan also states that with revenue shared from two other tax incremental financing districts, the downtown district “can remain financially positive should additional debt be incurred for these improvements.”